Karen Vogtmann – Trees, sphere systems and isoperimetric functions for Carte non disponible Date/heure Date(s) - 13 mai 2011 Catégories Pas de Catégories Outer space can be described as a space of actions on trees or as a space of sphere systems in a doubled handlebody. I will use both descriptions to give lower and upper bounds on the 2-dimensional isoperimetric function for $Out(F_n)$. The upper bounds work for arbitrary-dimensional isoperimetric functions, but for $n>2$ the optimal lower bound is not known.